Flaw detector mounting and control



Feb. 15, 1949 c. e. KAEHMS FLAW DETECTOR MOUNTING AND CONTROL 5 SheetsSheet 1 Filed May 15, 1945 fiweizz or BY I Feb. 15, 1949. c. e. KAEHMS FLAW DETECTOR MOUNTING AND CONTROL Filed May 15, 1945 5 Sheets-Sheet 2 s r ,w m h? m 0 0 ha AV 5% m ,r m C m m 3 6w I jai er/2e s Feb, 15, 1949. O c. G. KAEHMS 2,4 84

FLAW DETECTOR MOUNTING AND CONTROL Filed May 15, 1945 5 Sheets-Sheet 3 .fizzxerzior Cha/ ge zs G faekllzs Filed May 15, 1945 5 Sheets-Sheet 4 QQ QM r s m 5 w g 9? @Q m m r k u e 57 W .3 M Q3 5 ti; s 1m 0 .&\

RQ M 3 Feb. 15, 149. c. G. KAEHMS 2,461,984

. FLAW DETECTOR MOUNTING AND CONTROL Filed May 15, 1945 5 Sheets-Sheet 5 I 1. I l w 2/ 5'5 47 IHHHH Patented Feb. 15, 1949- FLAW DETECTOR MOUNTING AND CONTROL Charles G. Kaehms, Oakland, Calif., assignor, by

mesne assignments, to Southern Pacific Company, a corporation of Delaware Application May 15, 1945, Serial No. 593,858

18 Claims.

My invention relates to flaw detector apparatus for use on railway tracks and is directed to the means for mounting a detector assembly on a detector car for movement to and from a rail under the car.

The detector assembly consists of a brush carriage having an inductive pickup unit mounted between the front and rear brushes. The carriage is supported on the rail by flanged wheels, and may be raised from the rail when the car is traveling light between test locations. When in use for testing, the carriage rides on the rail with the wheel flanges urged against the gauge edge of the rail to properly align the rail energizer and testing equipment over the rail. Preferably also the brush carriage is urged downwardly against the rail to reduce the constant resistance between the brushes and the rail. While riding on the rail, the carriage must have free lateral and vertical movement relative to the car itself.

One object of my invention is to provide a structurally efiicient and reliable mounting for the detector assembly that will permit these various movements on the part of the detector assembly. Another object is to provide such a mounting that will maintain the detector assembly at a desired upright position relative to the top surface of the rail, regardless of the degree of extension of the detector assembly vertically or laterally and regardless of the tilt of the car.

In pressing a detector assembly laterally against the gauge side of the track, it is desirable to exert such lateral pressure at two longitudinal- A detector assembly of the present type includes a detector unit having one or more detector coils responsive to magnetic flux adjacent the rail under test, which detector unit is usually mounted on a carriage adapted for guiding contact with the rail. A further object of my invention is to provide for guiding and positioning such a detector unit for eflicient response to flaws and at the same time to provide such flexibility as will permit the detector unit to follow minor rail irregularities to a desirable degree.

Further objects of my invention relating to the control and correlation of the various movements of the detector assembly include the following:

To provide a control arrangement that will cause the mounting means to operate in a predetermined cycle involving both downward extension and lateral extension from a retracted position; to provide a single reversible manual control for such cyclic control; to provide automatic correlation ofthe vertical and lateral components of movement of the detector assembly; to provide automatic correlation of the means for pressing the carriage downward with the means for extending and retracting the carriage;

and to provide an eificient electrical system for controlling and correlating the different movements involved.

The above and other objects and advantages of my invention will be apparent in the following detailed description taken with the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative,

Figure l is a diagrammatic view showing selected parts of the structure employed in the preferred practice of my invention, together with a wiring diagram of the control system,

Figure 2 is a side elevation of a detector assembly mounted on a detector car as contemplated in the preferred practice of the invention,

Figure 3 is a fragmentary view partly in horizontal section of a portion of the mounting structure, the parts being positioned for normal operating extension of the detector assembly,

Figure 4 is a view partly in transverse vertical section showing the detector assembly in its retracted position, certain parts being omitted for clarification of illustration,

Figure 5 is a similar view showing the detector assembly in its downward movement approaching the rail,

Figure 6 is a similar view of the detector assembiy in its normal extended operating position,

Figure 7 is a fragmentary horizontal section on a somewhat enlarged scale taken as indicated by the line 'l'l of Figure 4, showing a transverse shifting mechanism in one position,

Figure 8 is a similar view with the mechanism in a second position,

Figure 9 is a portion of Figure 2 on an enlarged scale with certain portions broken away to reveal concealed structure, and

Figure 10 is a vertical transverse section taken as indicated by the line iliil of Figure 9.

General organization The principal parts of the particular detector assembly shown in Figures 2, 9 and 10 are a brush carriage, generally designated 20, for passing current longitudinally through a portion of the rail R, a detector unit 28 comprising one or more detector coils (not shown) in a box-likehousing for response to flaw-derivedvariations ,in the magnetic flux created by the longitudinal current, and a detector carriage 22 mounted on on the vertically movable support 23 by means or extended operating position for testing track,

the detector assembly is pressed downwardly against the track by suitable push rods 3| acting under air pressure.

The detector assembly The brush carriageshown in Figure 2 is of the well-known type having forward and rearward flanged wheels 32 to cooperate with the rail R as guide means, it being contemplated that the flanges of the two wheels will be pressed, laterally against the gauge side of the rail. A forward scratch brush 33 is provided to clear and clean the rail surface. Current enters the rail R from a forward set of six brushes 35, passes along the rail longitudinally and leaves the rail through a rearward set of six brushes 36. The various brushes are pivotally mounted on the carriage and are biased toward the rail by suitable biasing springs 31.

In the usual manner, the brush carriage incorporates suitable insulation to isolate the brush carriage electrically and to separate the two sides of the brush circuit. Such insulation, forexample is shown at 29 in Figure 9 and at 34 in Figure 10. It may be noted also in Figure 2 that the push rods 3| lead to insulating wooden beams 39.

For the purpose of mounting and guiding the detector carriage 22 for the detector unit 2!, the brush carriage has a pair of vertical guides 38 channel-shaped in cross section in which are slidingly mounted the opposite ends of a longitudinal guide beam 48. Fixed pins 4| extend through suitable slots 42 in the ends of the guide beam to limit the relative vertical movement thereof. Preferably suitable springs 43 are enclosed in the vertical guides 33 to press downward on the ends of a guide beam. Two threaded suspension rods 45 are adjustably but rigidly mounted on the guide beam 40 by means of suitable nuts 46 and have ball members 41 formed on their lower ends.

The detector carriage 22 is of arched construction, as best shown in Figure 9, and is provided with suitable sockets 48 for cooperation with the ball members 41. Suitable helical springs 50 surrounding the suspension rods 45 and acting between the guide beam 40 and the detector carriage serve to maintain. the ball members 47 in the sockets, these springs being stronger than the springs 43 acting on the ends of the guide beam. At the opposite ends of the detector carriage 22, suitable blocks are mounted thereon by insulating plates 52 and suitable shoes 53 are replaceably mounted on the blocks 5! in a wellknown manner by clamps 55 and bolts 56.

The detector unit 21 is adjustably mounted on the detector carriage 22 by means of threaded suspension rods 51 that extend through the detector carriage and are held thereon by stop nuts 58. The lower ends of the suspension rods 51 are adjustably secured to brackets 68 on the detector unit by means of nuts 6|. Preferably, the brackets cc are slotted to permit longitudinal adjustment of the detector unit relative to the suspension rods 51. The suspension rods 51 are axially movable relative to the detector carriage 22 but are normally pressed to their lowermost positions by suitable springs 62. The springs 62 are intended to be compressed only in emergencies, for example, when a relatively low rail joint causes the detector unit to make contact with the rail.

Itis apparent that the described manner of mounting the detector unit 2| on the brush carriage 2i} permits the detector unit to rock in a vertical longitudinal plane to follow irregularities in the configuration of the rail R and likewise permits the detector unit to swing for, the same purpose on a longitudinal axis determined by the two ball members 47 and their cooperating sockets 48.

Means for raising and lowering the detector assembly The vertically movable support 23 may be. in the form of an I-beam 65 adapted for cooperation with vertical guides 66 at its opposite ends. In the particular construction shown, the vertical guides 66 are channel members rigidly mounted on the under-structure of the detector carand each end of the I-beam 85 is provided with a shoe -51 that slides in the channel of the corresponding vertical guide and a second shoe 68 that slides against the inner face of the vertical guide.

The two previously-mentioned lift arms 25 are connected to corresponding lift links it which in turn are pivotally connected to suitable link brackets H on the upper surface of the I-beam 65. Each of the lift arms 25 is mounted on and operated by a corresponding shaft 12 that is journaled in suitable bearings 13 on the underframe of the detector car. Each of the two shafts :2 is controlled by a rocker arm 15 extending downwardly therefrom, the two rocker arms being pivotally connected to a horizontal lift rod Z53. For the purpose of adjustment, the lift rod it may be made in two sections between the two rocker arms f5 and the two sections adjustably interconnected by a turnbuckle 11.

As best shown in Figures 1 and 2, the lift rod it; is connected to one end of a lever 18 mounted on a pivot 8i! and the other end of the lever is connected to a piston rod 8! operated by a piston 82 in the lift cylinder 26.

It should be understood that the brush carriage on each side of the car is controlled by like apparatus, but for convenience the control equipment for one side only will be described.

As shown diagrammatically in Figure 1, compressed air from a supply pipe 83 may be ad mitted to the lift cylinder 26 through what may be termed a lift valve 85. The lift valve 85 is a three-way valve having one position for placing the lift cylinders under pressure and a second position for releasing compressed air from the lift cylinders to the atmosphere, the second posit on being shown in Figure 1. A suitable spring 81 urges the operating lever 88 of the'lift valve 83 to the release position of the valve and a lift lease the latch shoulder 19 when the latch mechanism is energized. When the detent 86 is in its raised or extended position, it is yieldable to permit the latch shoulder I9 to move across it into a latched position.

Means for moving the detector assembly transversely Each of the previously-mentioned two sets of parallel linkages 21, 'as best shown in Figures 4, 5 and 6, includes a transverse yoke SI that is fixedly mounted on the I-beam 65. The two ends of each yoke 9i carry pins 92 on which are mounted parallel links 93 and 94. The lower ends of the parallel links 93 and 94 carry pins 95 that are mounted in suitable bearing sleeves 96 integral with a plate 91, the plate being attached to the top of the brush carriage 20 by a number of cap screws 98. The described parallel linkages 27 are sufficiently loose at the joints to permit the detector assembly to rotate laterally slightly as may be required to conform to a curve in the track.

To limit the lateral movement of the parallel linkage inwardly with respect to the center of the car, at least one of the inner parallel links 94 may be formed with a finger I overhanging the corresponding yoke 9! to carry an adjustable stop screw I0! for movement against the yoke. The stop screw may be provided with a suitable locking nut I02.

The previously-mentioned two pairs of toggle arms 28 constitute operating means at spaced points along the vertically movable support 23 and these two operating means are connected to a force-transmitting means in the form of an operating rod I05. to swing laterally on the tWo sets of parallel linkages 27, it is merely necessary to shift the operating rod I 0'5 from the position shown in Figure '7 to the position indicated in Figure 8, thereby causing the two pairs of toggle arms to spread.

Each of the individual toggle arms 20 comprises a pair of spaced fiat links, as shown in Figures 4-6. Each pair of the toggle arms 28 is connected to a suitable pivot pin I00 on the operating rod I05, and, at their outer ends, the toggle arms are pivotally connected to the trunnions of suitable trunnion members I07, each of the trunnions I01 being mounted for pivotal action about an axis perpendicular to the axis of its trunnion connections with the toggle arms.

As indicated in Figure 7, one of the trunnion members I07 associated with each of the pairs of toggle arms may be rotatably mounted on a projecting end of one of the lower pivot pins 95 of the previously-described parallel linkage, the pin being formed With a radial collar I08 in abutment with the adjacent fixed bearing sleeve 35 to take the thrust of the toggle action. The other trunnion member I0'I associated with each of the pairs of toggle arms is shown rotatably mounted To cause the detector assembly to the rod I by virtue of a pair of confining collars Ill that are adjustably anchored on the rod by suitable set screws I I8. It is apparent that movement of the piston I I2 to the left, as viewed in the drawings, will shift the operating rod I05 to the left and thereby expand the toggle arms 28 to cause the detector assembly to be swung laterally outwardly of the car on the two parallel linkages 21. Suitable means may be employed to limit movement of the toggle arms beyond their normal range, for example a stop screw I I9 (Figs. 4, 5 and 6) positioned on the parallel linkage to abut the lift beam 35. Preferably, a suitable helical spring I is housed in the push-over cylinder 30, as indicated in Figure 3, for the purpose of urging the piston to this leftward position and compressed air is admitted to the cylinder to move the piston to the right when it is desired to retract the detector assembly inward.

Figure 1 shows diagrammatica ly the arrangement for controlling the admission of air to the push-over cylinder 30. Compressed air in a pipe I2I from the previously-mentioned supply pipe 83 is controlled by a three-way push-over valve I22 which is connected on its outlet sideto a pipe I 23 leading to the push-over cylinder 30. A suitable spring I23 acting on the lever IZ'I tends to hold the push-over valve I22 in its release position to permit the spring I20 to control the lateral position of the detector assembly. Whenever a push-over solenoid I28 also connected to the lever I2? is energized, the solenoid swings the lever to a pressure position of the valve admitting compressed air to the push-over cylinder 30 to drive the piston II2 to the right thereby to retract the detector assembly laterally.

For the purpose of adjustment, the operating rod I 05 may be made in two sections adjustably interconnected by a turnbuckle I30. The operating rod I05 may also incorporate suitable yielding means which may be placed at various points between the fork member H6 and the connec tions between the parallel linkages 21 and the brush carriage 20,or at least at a point between the fork member and one of the connections. The purpose of such yielding means is to permit a s ight amount of lateral rotation on the part of the brush carriage to follow changes of direction of the rail R. In the absence of some'such provision, the rigidity of the brush carriage mounting will permit only one of the two flanged wheels 32 to be pressed against the gauge side of the rail on a curve in the track.

In the present construction, such a desired yieldin action may be achieved by breaking the operating rod I05 to form two normally spaced ends I3! and I 32, as indicated in Figure 3. The end I3I is formed with a circular head I33 and the end I32 is provided witha cylindrical extension I35 that slidingly houses the circular head I33. A suitable guide and stop bushing I36 is threaded into the end of the cylindrical extension I 35 and a spring I37 is housed in the cylindri-cal extension I35 to urge the circular head I33 toward the bushing I36.

.rod liii which houses a spring I39. I39 acts between a bushing Hi4 and a head I49 between the fork and the second pair of toggle arms 28. As shown in Figure 3, this second yielding means may likewise comprise a cylindrical extension on an end portion of the operating The spring on a second end portion of the operating rod. When the detector assembly is in its elevated 01" retracted position, the two springs I31 and its in Figure 3 are at their positions of maximum confined length. The two springs are pre-loaded .or confined at substantially less than their free lengths. When the detector assembly is moved laterally toward the rail by the push-over spring I26, the two springs it! and I39 yield after the -wheels 32 of the brush carriage contact the gauge side of the rail and, in the normal extended position of the detector assembly, the two springs I31 and 139 are normally partially compressed. as shown in Figure 3. When the detector assembly is traversing a curve, the detector as- ;sembly will rotate laterally to a slight extent as required to conform with the changing curvature of the rail and, of course, one of the springs Ili'z or I39 will correspondingly be compressed to greater than normal degree while the other spring will expand from its normal length. To

provide the required action, the two springs it": and E39 must, of course, be somewhat weaker than the push-over spring I28 since the pushover spring normally overcomes both of the springs I31 and I39.

The hold-down means pressed air from the supply pipe 83 and delivers the air to a pipe I41 leading to the two holddown cylinders M which are connected to opposite ends of the brush carriage. A spring I50 acting on the valve lever I5! urges the valve to its release position to permit freedom of movement of the push rods 3| while a hold-down solenoid E52 is connected to the valve lever to move the valve to its pressure position for admitting compressed air to the hold-down cylinder I40.

The electrical control system The desired cycle of operation may be understood from Figures 4, 5 and 6, showing successive positions of the brush carriage in moving from its vertically and laterally retracted position into normal operating position in contact with the rail E. Figure 4 shows the retracted position at which the vertically movable support 23 is held elevated either by engagement of the latch shoulder 19 with the detent 84 or by air pressure in the lift cylinder 26. In the position shown in Figure 4, air pressure in the push-over cylinder 39 causes the piston I I2 in the push-over cylinder to compressthe spring 120, the two .pairs of toggle arms 28 being in their contracted positions.

.To initiate the cycle of operation, the vertically movable support 23 is released to gravitate downwardly toward the positionshown in Figure 5. Such release may be made by disengaging the detent 84 from the latching shoulder 19, but

.in normal operation is accomplished by energizing the liftsolenoid :98] to release air from the lift cylinder 26. -As the detector assembly approaches the position shown in Figureifi in its downward movement, the push-over means acts -the push-over solenoid I28 to release air from the push-over cylinder 30 thereby to permit the spring I20 in the cylinder to actuate the operating rod. 25. for the two pairs of toggle arms 28.

In the preferred form of my control system, two switches operate in response to the vertical movement represented by Figures 4 and 5. One of these switches is .a switch A shown diagrammatically' in Figure 1, as comprising a'fixed contact id3 and a switch arm I58. The switch is biased toits closedposition by an up er spring Hi1. and is opened by downward movement of a substantially stronger spring I58, the lower spring being adapted for downward movement by the vertically movable support 23 at a suitable ;.ireviously-mentioned lower spring I58 for operating the switch A is connected to the upper end of a rod use that extends loosely through a guide sleeve 64 on a flange I61 extending laterally from the vertically movable support 23. In the particular construction shown in Figures 4, 5 and 6,'the flange IE1 is integral with one of the yokes ill of the parallel linkage. Adjustably mounted on the lower end of the rod 256 below the flange 661 is a nut I68 for abutment against the underside of the guide sleeve I64 to operate the switch A in opposition to the biasing spring E51. At the desired point in the downward move ment of the vertically movable support 23, the abutment of the nut against the guide sleeve [64 draws the lower spring I58 downward to operate the switch A. Normally, the lower spring I58 does not yield to any significant extentbut may do so whenever the detector assembly descends to abnormal extent because it misses the rail.

The switch B may be operated by a similar structural arrangement but, preferably, switch B closes later in the downward movement than the opening of switch A, so that the brush carriage will be biased against the gauge side of the rail beforethe push-down means becomes effective.

The wiring diagram in Figure 1 includes, besides switches A and B, a switch I79 for energizing or deenergizing the whole system, a two-blade main control switch or lift switch I7I insid the car, an auxiliary switch C accessible outside the car, a latch switch I 72 and a relay having a relay coil I73 and two relay arms I75 and I78. The relay arm I 75 of the relay cooperates with a fixed contact I77 for electrically locking the relay independently of the lift switch I'll. When the relay is energized, the relay arm I79 is held against a contact I78 for energization of the push-over solenoid I 28. When the relay is deenergized, the relay arm I76 drops against a second contact I99 in a circuit for energizing the hold-down solenoid I52.

The control system is energized by two leads I8I and I82 from a suitable source such as a generator I83, the lead I82 being controlled by the previously-mentioned switch I79. The two blades of the lift switch I7I are connected to the lead I82 by a wire I95, the wire I85 being broken by the switch C. One of the blades of the lift switch I7l moves against a contact that is connected by a wire I89 both to the relay coil I73 and the fixed contact I77 while the other blade of the lift switch moves against a contact from which a wire I87 leads to the previously-mentioned auxiliary switch 0, The closing of the lift switch I'II completes the following lift circuit for energizing the lift solenoid: lead IIlI, lift solenoid 90, wire I98, wire I87, one blade of lift switch I7I, wire I 85 and auxiliary switch C to the second lead I82. In the closing of the lift switch I'll, the second blade completes the following circult to energize the relay coil I73: lead I8I, wire I99, relay coil I73, wire I85, lift switch I7I, wire I85 and switch C to the second lead I82.

If the lift switch I'll is closed while the switch A is closed, that is to say, if the lift switch is. closed while the detector assembly is elevated above the relatively low position for opening the switch'A. the energization of the relay coil I73 will establish a circuit to lock the relay in its energized position independently of the lift switch I7I. The locking circuit may be traced as follows: lead I8I. wire I99, relay coil I73, wire I8I5, contact I77, relay arm I75, wire I9l, arm I56 of switch A. fixed contact I53 and a wire I92 to the second lead I82.

Whenever the relay coil I73 is energized either by the previously-described lift circuit through the lift switch I7I or by the described locking circuit, the following push-over circuit is completed: lead I8I, wire I84, push-over solenoid I28, wire I95, contact I78, relay arm I76 and wire I92 to the second lead I82.

When the relay coil I73 is deenergized while the switch B is closed, that is to say, whenever the lift switch I7I is open while the detector assembly is at a relatively low level to hold the switch B closed, the following hold-down circuit is established: wire I ill, wire I99, hold-down solenoid I52, wire I97, switch arm I62 of switch B, fixed contact I60, wire I98, contact I89, relay arm I79, wire 299 and wire I92 to the second lead I92.

It will be noted that the circuit for controlling the lateral actuating means, i. e., the push-over circuit for causing pressure to be built up in the push-over cylinder 39 has, in effect, two control switches, a first control switch being the relay arm I75 and a second control switch being the switch A, and that the function of the latter control switch A is to cause the carriage to remain laterally retracted independently of the position of 10 the main control switch when the carriage is elevated. It will also-be noted that the circuit for controlling the actuating means to press the detector assembly downward againstthe top of the rail, i. e., the push-down circuit has, in effect, two control switches, one control switch being the relay arm I79 and the other being the control switch,B. The function of the control switch B is to cause the push-down means to remain ineffective when the detector assembly is at elevated positions.

The latch circuit which when energized retracts the detent 84 to an inefiective position includes a wire I89 from the lead I 8I to the detent mechanism, a wire I93 from the detent mechanism to the latch switch I72 and a wire I94 from the switch I72 to the second lead I82.

Operation Normally the switch I72 for controlling the energization of the system as a whole is closed and the latch switch I72 is closed to keep the latching detent 84 in retracted ineffective position. Normally when the detector assembly is in its retracted or elevated position, the lift switch I'II is closed to hold the vertical support 23 elevated without need for the latch detent 84. Since this switch I7! is closed at such time, the relay coil I73 is energized and therefore the push-over circuit is energized to maintain the push-over cylinder 3!] under air pressure to hold the detector assembly laterally retracted. The hold-down circuit is not energized because the relay arm I76 is held in its upper position by the energized relay coil I73. Since the detector assembly is elevated, the switch A is closed to complete the locking circuit at this time and the switch B is open.

To cause the cycle of operation for lowering the detector assembly in the manner indicated by Figures 4-6, it is necessary merely to open the lift switch I7I. The opening of the lift switch does not deenergiee the relay coil I73 because the switch A is closed to maintain the locking circuit through the relay coil. Since the relay coil re-' mains energized, the opening of the lift switch I7I does not permit the relay arm I76 to close the hold-down circuit. The opening of the lift switch I7I does, however, deenergize the lift solenoid 99, whereupon the spring 87 moves the lift valve to its release position permitting air to e cape from the lift cylinder 29. The release of air from the lift cylinder permits the vertically movable Support 23 to gravitate downwardly.

The downward movement of the detector assembly by gravity eventually causes switch A to be opened mechanically to break the locking circuit, thereby caus ng the relay coil 73 to be deenergized. The cleenergization of the relay coil causes re ay I75 to drop, thereby opening the pushover circuit to deenergize the push-over relay I 28. Upon deenergization of this relay, the pushover valve I22 moves to its release position permitting air to escape from the push-over cylinder 39 and permitting the spring I29 in the push-over cylinder to actuate the toggle arms 28 for shifting the detector assembly outwardly.

The continued lowering of the detector assembly is along an inclined path, as indicated by the arrow in Figure 5, because of the toggle action. As the detector assembly approaches actual contact with the rail R in this final lowering movement, switch B is mechanically closed to complete the hold-down circuit, whereupon the hold-down solenoid I52 is energized to shift the hold-down valve M9 to its pressure position. The admission 11. compressed air to the hold-down cylinders 5% causes the detector assembly to (repressed downward against the top surfaceoi the rai The various moving parts of the structure the electrical system are then positioneda. dicated in Figure 1.

Thereverse cycle of operation for retracting the detector assembly upwardly andlaterallyjis initiated byv simply closing, the lift switch ill. The closing of the lift switch completes the lift circuit to energize the lift solenoid.89;c1hereupon compressedair is admitted to the lift cylinder 23 to move thesupport means 23 upward. The closing of the lift switch I'll also energizes the relay coil I13 thereby to lift the relay arm I16 to open the hold-down circuit so that air may be released from the hold-down cylinders I40.

The lifting of the relay arm 51E closes the pushover circuit to energize thepush-cver solenoid I28. Theiconsequent shifting. of the push-over valve 22 to its pressureposition causes-air to circuitiis not requiredduring this reverse cycleof operatiom The fact that the push-over cylin-- der is normally under pressure when; the detector assembly is elevated; thereby holding the detec tor assembly retractedlaterally inward inoppositios tothepush-over spring 125,1'1S0f advantage lac-- cause, in the firstplacatnecessity for re rooting thedetector assembly laterallyduring the lower" mg -movement isiunnecessary, and, because, in

theisecondcplace, theair pressure against the pusheover.piston=-tends-to keep the various elements of the pushover mechanism iromrattling while the detector: car is traveling at relatively highspeed to or froma test location.

An operator on theoutside of a detectorcar maycausellowering of thedetectorlassembly from its normal retracted position byopening switch C. If: the detector assembly'is held in elevated positionnby, the detent .S Lthe latch switch I22 being open, the operator may release the detector assembly for downward movement by momentarily closing the lift circuit to take latching pressure off thedetent member, then closing the latch switch H2 to retract thedetent member and finally reopening thelift switch H l It is important tonote that since the support means 23 is rigidlyguided in its up andidown movement on a straight-line path, and, since the detector assembly is mounted on the support it. by parallel linkages, the detectorassembly will be maintained at aconstant angle-relative to the car bottom at all positions of the detector assembly. This constant position is substantially perpendicular to the car bottom, since the car bottom is substantially parallel to the plane of the track under the car, the arrangement ins-u *s that the detector asesmbly will be at a position to rest squarely on the corresponding rail, regardless of the degree to which the car be tilted by banking oi the track.

My detailed description of a preferred embodiment of the invention for the purpose oi disclosure and to illustrate the principles involved 12 will suggest to those skilled in the art various changes and substitutions under basic ccncept, and I reserve the right to all suchfit1liitures from my description that lie within Ll scope of the appended claims.

I claim:

1. In a flaw detector car, a carriage adapted to travel along the rail under the a sup port for said carriage, means to raise and lo said support relative to the car, means i .1 a parallel linkage suspending said carria c in, said support for lateral movement of relative to the support while maintaining carriageat a substantially constant eagle re a ve to the plane of the car bottom, and means. to said carriage laterally relative to said so 2. In a flaw detector car, a carriage ad .1 1"- travel along a rail under the car, a support under said car, means to raise and lower support along a straight line path, means including a parallel linkage suspending said carriage from said support for lateral movement of the carriage while maintaining the carriage at a substantially constant angle relative tothe plane of the (as bottom, and means mounted on said support to act between the support and the carriage for causing lateral movement of the carriage.

3. In a flaw detector car, a carriage adapted to travel alonga rail under the car in contact with the gauge side of the rail, means including a allel linkage for mounting, said carriage on the car for movement of the carriage transversely of the car to and from said rail, and actuatinr means including a toggle linkage to move said carriage on said parallel linkage and to press the carriage toward said gauge side of the rail.

4. In a detector car, a carriage adapted to travel along'a rail under the car in contact with the gauge side of the rail, means mounting said carriage on the car with freedom for both vertical movement and transverse movement, means to raise and lower said carriage, and means including a" toggle linkage to move the carriage laterally, while the carriage is being raised and lowered and topress the carriage against said rail.

5. In a detector. car, a carriage adapted .to travel along a rail under the car, a forward guide means and a rearward guide means on said carriage for contact with the gauge side of the rail, means to raise and lower said carriage, a forward operating means and a rearward operating means connected with said carriage at longitudinally spaced points to move the carriage laterally toward and away from said rail and to press said two guide means against the rail, actuating, means, means connecting said actuating means with said two operating means to apply force thereto, and yielding means effective between said actuating means and at least one of said spaced points on the carriage to yieldingly transmit force to the carriage thereby permitting relative lateral .movement of said two guide means to'keep both guide means in contact with the gauge side of the rail on a curve.

6. In a detector car, a carriage adapted to travel along a rail under the car, a forward guide means and a rearward guide means on said carriage for contact with the gauge side of the rail, means to raise and lower said carriage, a forward operating means and a rearward operating means connected with said carriage at longitudinally spacedipoints to move the carriage laterally toward and away from said rail and to press said two guide means against the rail, forcetransmitting means interconnecting said two operating means, and actuating means connected to said force-transmitting means at a point of connection thereon to apply force thereto, said transmitting means being longitudinally yieldable between said point of connection and at least one of said operating means thereby permitting rela tive lateral movement of said two guide means to keep both the guide means in contact with the gauge side of the rail on a curve.

'7. In a detector car, a carriage adapted to travel along a rail under the car, a forward guide means and a rearward guide'means on said carriage for contact with the gauge side of the rail, means to raise and lower said carriage, parallel linkage connected to the carriage for lateral movement of the carriage with the carriage at a constant angle relative to the plane of the car bottom, a forward operating means and a rearward operating means connected with said carriage at longitudinally spaced points to move the carriage laterally toward and away from said rail and to press said two guide means against the rail, force-transmitting means interconnecting said two operating means, and actuating means connected to said force-transmitting means at a point of connection thereon to apply force thereto, said transmitting means being longitudinally yieldable between said point of connection and at least one of said operating means thereby permitting relative lateral movement of said two guide means to keep both the guide means in contact with the gauge side of the rail on a curve.

8. In a flaw detector car, a carriage adapted to travel along a rail under the car, a forward guide means and a rearward guide means on said carriage for contact with the gauge side of the rail, a support for said carriage, means to raise and lower said support relative to the car, means including a forward parallel linkage and a rearward parallel linkage suspending said carriage from said support for lateral movement of the carriage relative to the support with maintenance of the carriage at a substantially constant angle relative to the plane of the car bottom, a forward operating means and a rearward operating means on said support connected with said carriage at longitudinally spaced points to move the carriage laterally toward and away from said rail and to press said two guidemeans against the rail, force-transmitting means interconnecting said two operating means, and actuating means on said support connected to said force- 'transmitting means at a point of connection thereon to apply force thereto, said transmitting means being longitudinally yieldable between said point of connection and at least one of said operating means thereby permitting relative lateral movement of said two guide means to keep both the guide means in contact with the gauge side of the rail on a curve.

9. In a flaw detector car, a carriage adapted to travel along a rail under the car with a part thereof in abutment with the gauge side of the rail, a support for said carriage, means mounting said support on the car for raising and lowering of the support while maintaining the support at a substantially constant orientation relative to the car, means acting between the car and said support to raise and lower the support, means mounting said carriage on said support for lateral movement of the carriage while maintaining the carriage at a substantially constant angle relative to the support, and means acting between said support and carriage to move the carriage laterally to and from said rail on the last-mentioned mounting means and to press the carriage against the gauge side of the rail. 19. In a flaw detector car, a carriage adapted to travel along a rail under the car with a part thereof in abutment with the gauge side of the rail, a support for said carriage, means mounting said support on the car for raising and low- -ering of the support while maintaining the support at a substantially constant orientation relative to the car, a first means acting between the car and said support to raise and lower the support, means mounting said carriage on said support for lateral movement of the carriage while maintaining the carriage at a substantially constant angle relative to the support, a second means acting between said support and carriage to move the carriage laterally to and from said rail and to press the carriage against the gauge side of the rail, and a third means acting between the car and the carriage to press the carriagedownward against the top of the rail.

11. In a flaw detector car; a carriage adapted to travel along a rail under the car with a part thereof in abutment with the gauge side of the rail, a support for said carriage, means mounting said support on the car for raising and lowering of the support while maintaining the support at a substantially constant orientation relative to the car, a first means acting between the car and said support to raise and lower the support, means mounting said carriage on said support for lateral movement of the carriage while maintaining the carriage at a substantially constant angle relative to the support, a second means acting between said support and carriage to move the carriage laterally to and from said rail and to press the carriage against the gauge side of the rail, a third means acting between the car and the carriage to press the carriage downward against the top of the rail, and means to control and correlate said first, second and third means for a cycle of operation whereby said third means 4 may act only when said support is lowered.

12. In a flaw detector car, a carriage adapted to travel along a rail under the car with a portion of the carriage in abutment with the gauge side of the rail, means mounting said carriage for up and down and lateral movement relative to the car, actuating means to raise and lower the means, a main control switch in said circuit movable between a first position for raising the car--;

riage and a second position for lowering the carriage, a lateral actuating means to move the carriage laterally toward and way from the rail, a circuit means for controlling said lateral actuating means, a first control switch in said circuit I means to cause the carriage to retract laterally in response to movement of said main control switch to said first position, and a second control switch in circuit means to cause the carriage to remain laterally retracted independently of the position of said main control switch when the carriage is elevated.

13. In a flaw detector car, a carriage adapted to travel along a rail under the car with a portion of the carriage in abutment with the gauge side of the rail, means mounting said carriage for up and down and lateral movement relative to the car, actuating means to raise and lower the carriage, a circuit for controlling said actuat ing means, a main control switch in said circuit.

carriage '1 and a, second position for lowering the carriage, a lateral actuating means to extend retract the carriage laterally tov-Jard and away from'therail, circuit means for contrc g said lateralactuating means, a first control switch said circuit means to take a position for latertraction of the carriage response to move: of-Jsaid main control switch to said first posi and'cto take a position for lateral retraction of the "carriage in response to movement of so? main control switc to second position, and a second control sw ch in said circuit scans to cause the carriage to remain laterally retracted independently of the po it-ion of said ii-tiajln control switch when c: age is elevated.

14-. In a flaw tor car, a carriage adapted toztravcl along a rail under the car with a portion' of the carriage in abutment with the gauge sideof the rail, means mounting said carriage forrup and down movement relative to the car, actuating means to raise and lower the carriage, eclrcuit for con olling said actuating means, a main control switch in said circuit movable between a first position for raising the carriage and a second position for lowering the carriage, an actuatingmeans to press the carriage downward against the top of the rail, a circuit for controlling said pressure-actuating means, a control switch in said latter circuit to cause said pressure-actuatingmeans to become ineffective in response to movement of said main control switch to said first position, and a second control switch in said second: circuit to cause said pressure-actuating means to remain inefiective independently of the position of said main control switch when said carriage is elevated.

15. In a flaw detector car, a carriage adapted to travel along a rail under the car with a portion of the carriage in abutment with the gauge side of the rail, means mounting said carria e for up and down movement relative to the car, actuating means to raise and lowe circuit for controlling said actuating means, a main control switch in said circuit movable between a first position for raising the carriage and a second position for lowering the carriage, a pressure'means to press the carriage downward against the top of the rail, a circuit for controlling said pressure means, a control switch for said latter circuit to take a position in response to movement of said main control switch to said first position to cause said pressure means to he ineffective and to take a position in response to movement of said main control switch to said second positionto cause said pressure means to be effective, and a control switch for said latter ci' cult to cause said pressure means to remain ineffective independently of the position of said main control switch when the carriage is elevated.

16; In a flaw detector car, a carriage adapted to travel along a rail under the car with a portion of the carriage in abutment with the gauge sideof the rail, means mounting said carriage for up and down and lateral movement relative to the car, actuating means to raise and lower the carriage, a circuit for controlling said actuating means, a main control switch in said circuit movable between a first position for raising the car 'iage and a second position for lowering the carriage, a lateral actuating means to move the carriage laterally toward and away from the rail, a circuit for controlling said lateral actuating. means, a control switch in said latter circuit movable to two positions, one position for causing.

1' the can-1 a];

the carriage .to -be -laterally retracted and the otherposition for. causing the carriage to be laterally extended, means to make said secondmentioned control switch responsive to said main 5 control switch whereby the second-mentioned switcl'i .moves. to said one position in response to movement of the main control switch to its first position, and meansto make said secondmentioned switch non-responsive to said main control switch whenever the carriage is substantially fully elevated.

17. Ina flaw detector car, a carriageadapted to travel along a rail under the car with a portionof the carriage in. abutment with the gauge 5 side of the rail, means mounting said carriage for upand down movement relative to the car,

actuating means to raise and lower the carriage, acircuit for controlling said actuating means, a

main. control switch in said circuit movable bev tween a f st position for raising the carriage andasecond position for lowering the carriage, an actuating means to .press the carriage downward against the top of the rail, circuit means for controlling said pressure actuating means, a.-

first control switch in said circuit means responsiveto said main control switch to cause deenergloat-ion. of said pressure actuating means when said-main. control switch is moved to said first position, and a second control switch in said ciraoccuit-means in series with said first control switch adapted to open in response to upward movement of the carriage thereby to make said pressure actuatingv means non-responsive to the main control switch when the carriage is fully elevated.

18. In a flaw detector car, a carriage adapted to travel along. a rail under the car with a portion of the carriage in abutment with the gauge side of the rail, means mounting said carriage for-up and down movement relative to the car, -1 actuating means to raise and lower the carriage,

a circuit for controllingsaid actuating means, a. main switch in saidcircuit movable between a.

first positionior raising the carriage and a second position for. lowering the carriage, a second actuating means to press the lowered carriage downward against the top of .the rail, a second-circuit for controlling said second actuating means,- acontrol switch in said second circuit movable to two positions, one position for energization of.

the second actuating means and the other position 101' deenergization of the second actuating means, means to make said second-mentioned control switch responsive to said main control= switch to cause deenerg zation of said second actuating means when said main control switch is moved to its first position, and means res onsive to upward movement of the carriage tb make said secondcontrol switch non-responsive to said ma n control switch when the car age is elevated.

CHARLES G. KAEHMS.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED' STATES PATENTS Frickey et a1. Nov. 13, 1945' 

